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Thread: Recirculating pump install questions? (PIC)

  1. #1
    DIY Junior Member Handiman's Avatar
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    Question Recirculating pump install questions? (PIC)

    Hey, I have a 75 gallon Bradford White natural gas WH and have questions about my GRUNDFOS recirculating pump. It is a 20 year old (UP 15-18 SU) model. Is the best way to install these by tying into the return line on the bottom of the WH discharge/drain? At least I think that is the return line (must be)? Also, what is the longevity of these pumps? It takes about 1.5 minutes for hot water in the kitchen (farthest from WH). Would installing those new (plastic) instant hot valves under the farthest sinks upstairs and downstairs help circulate the hot water more? Also thinking about replacing this older pump with the new WATTS recirculating pump adding the valves as well.

    Here is a PIC, is this the preferred method for placement of the recirculating pump? Kind of like this diagram?
    http://www.grundfos.com/web/homeus.n...ag/PAVA-53RM5Z


  2. #2
    Moderator & Master Plumber hj's Avatar
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    IF that is the original pump, CHANGE IT and the check valve. They should both be worn out by now. The plastic valves at the sinks are NOT designed for your system and would do NOTHING except cost money and could create problems rather than solve them. How fast water gets to your sink is entirely dependent upon WHERE the circulation system is connected to the hot water piping and WHERE the sink is relative to that point.

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    Plumber Cass's Avatar
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    I am going to guess that the expansion tank is shot also....maybe not but the odds are it is...

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    DIY Junior Member Handiman's Avatar
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    Question

    Thanks for the replies. Sorry forgot to mention the WH and expansion tank are new (recently installed), only the 20 year old GRUNDFOS was transfered over from the old leaking WH.

    1. This (return line) is the best spot to install a recirculating pump at the WH drain?

    2. So with having a RETURN LINE there is no need (advantage) for those plastic valves under the farthest sinks?

    3. Best to just only install a new GRUNDFOS recirculating pump then?

    4. Also, would it be better to have a timer or aquastat, or both?

    Thanks again

  5. #5
    Retired Defense Industry Engineer jadnashua's Avatar
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    Different brands control the recirculation in different ways. Some turn the pump off by sensing when you have hot water where you want it. Some leave the pump running constantly, and use a thermostatically controlled valve to control the recirculation (more flexible, since you can put a valve at each point of use rather than monitor just one point). So, not knowing exactly how the one you have works, I can't say. You don't want to try to mix systems, though. The pumps chosen for recirculation have a small enough head so that they won't be hurt if they run when the valve is closed. Any replacement pump must be rated for use on potable water...this means either SS or bronze (and if you live in CA, it's probably going to be hard to find a bronze one because of the lead issues). These are a lot more expensive than a typical cast circulator used in a hydronic heating system.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  6. #6
    DIY Junior Member Artcraft's Avatar
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    Hi
    it seems to me that minuit and a half with a re-circ line is wrong. The line must not of been set up very well or the pump is not working. when you replace the pump, I would replace with timer and aquastat, will be much more efficient and you dont run as great a risk of erroding the pipes. I just replaced a loop because the previous plumber dident ream well enough and it erroded the copper running 24/7

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